precondition vs proviso

precondition and proviso both are nouns.

Word	Noun	Adjective	Verb	Adverb
precondition	Yes	No	Yes	No
proviso	Yes	No	No	No

As nouns, proviso is a hyponym of precondition; that is, proviso is a word with a more specific, narrower meaning than precondition:

precondition: an assumption on which rests the validity or effect of something else
proviso: a stipulated condition

Other hyponyms of precondition include boundary condition, provision.

precondition (noun)	proviso (noun)
a condition that is a prerequisite	a stipulated condition
an assumption that is taken for granted
an assumption on which rests the validity or effect of something else

precondition (verb)	proviso (verb)
put into the required condition beforehand